MARINE FOOD FISHES 113 



In certain tropical flat fishes the eye appears to 

 travel right through the head to the upper surface. 

 This is due to the fact that in these fish the fin is pro- 

 longed on to the head. At first one eye is on either 

 side, but when the cranium rotates the eye from under- 

 neath is carried through the fleshy part of the fin. 



Attached to the biological station at Port Erin in 

 the Isle of Man, is a fish hatchery. Here, in two large 

 ponds some four hundred plaice spawn every year. The 

 spawning extends over a period of about six weeks, and 

 during this time the floating eggs are periodically 

 collected by means of a large surface net. The eggs are 

 then transferred to the hatchery and in due course the 

 larval fish that hatch are turned into the sea. In 1910, 

 over eight million larvse were thus hatched and released 

 during the season. As might be expected, several eggs 

 escape collection. These hatch, and grow to small plaice 

 in the ponds. In April and May, 1909, through the kind- 

 ness of Professor Herdman and the assistance of Mr. 

 Chadwick, I was able to collect several of these plaice 

 larvse and obtain photographs of them in all stages of 

 their transformation. 



Until my arrival at Port Erin, I had no idea that 

 I should have such a grand opportunity for photograph- 

 ing these larvae, and, in consequence, was unprovided 

 with a suitable apparatus for the work. With the 

 assistance of the local carpenter, however, I constructed 

 a wood, wire and brown-paper extension to my reflex 

 camera, and using an acetylene bicycle lamp as an 

 I 



